This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-302033, filed Oct. 25, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a solution processing apparatus, for example, for supplying a developing solution to the surface of a substrate coated with a resist and subjected to exposure processing to perform developing processing.
A mask for forming a circuit pattern on the surface of a semiconductor wafer (hereinafter referred to as a wafer) or an LCD substrate of a liquid crystal display is formed by the following process. Namely, a photo-resist solution (hereinafter referred to as a resist) is first applied on the surface of the wafer, and light or the like is irradiated on the photo resist film. If the resist is negative, for example, a portion exposed to the light is cured, and a portion which is not cured, that is, a portion in which the resist is easily soluble, is dissolved by a developing solution, thereby forming a desired mask. A developing processing apparatus includes a spin chuck for rotating the wafer while suction-holding it and a developing solution supply nozzle for supplying a developing solution to the wafer on the spin chuck.
As a developing solution supply nozzle used in the aforesaid developing process, a supply nozzle in which a large number of discharge ports are arranged over a length corresponding to the diameter of the wafer has been hitherto used.
In the developing process by means of this supply nozzle, the center of the wafer is first vacuum-sucked and horizontally held by the spin chuck. The supply nozzle is positioned so that the discharge ports are situated, for example, 1 mm higher than the surface of the wafer at a central portion of the wafer, and the wafer is rotated 180 degrees while the developing solution is being supplied to the central portion of the surface of the wafer in a diameter direction from the discharge ports. Thus, the developing solution is spread all over the wafer while being discharged to the central portion over the diameter of the wafer, and heaped up. A the same time, a film of the developing solution with a predetermined thickness is formed on the entire surface of the wafer.
To secure the uniformity of line width, however, the process of heaping up the developing solution on the entire upper face of the wafer has heretofore needed to equalize the total retention time of the heaped developing solution as much as possible. Therefore, it is necessary to apply the developing solution to the wafer quickly, and thus the supply pressure of the developing solution is raised.
According to a conventional developing processing method, however, in view of uniform discharge, the diameter of a discharge port of the developing solution supply nozzle is small, and supply pressure is set at a high pressure, whereby discharge flow velocity becomes high. As a result, there is a possibility that an impact on a portion to be dissolved of the surface of the wafer is strong at the time of initial discharge onto the surface of the wafer, thus lowering the uniformity of line width.
Another method of using the same developing solution supply nozzle and spin chuck as the aforesaid ones is examined. This method is a scan method in which the supply nozzle is moved to the outside of the peripheral edge of the wafer horizontally held by the spin chuck and positioned there, and from this position, moved to the outside of the opposite side of the wafer peripheral edge while discharging the developint solution.
Such a scan method is similar in that the discharge pressure of the developing solution onto a substrate is high, and there is a possibility that micro bubbles appear by an impact caused by the supply of the developing solution to the surface of the substrate. Micro bubbles cause poor developing by touching a pattern on the wafer, and hence it is desirable to inhibit the appearance of micro bubbles as much as possible.
When the wafer is vacuum-sucked from the center of its back side by the spin chuck, a little distortion occurs in the wafer, whereby the developing solution supplied to the surface of the wafer tends to concentrate at the center. Accordingly, a solution film at the central potion of the wafer is thicker than at the edge portion, which causes a problem that line width becomes ununiform.
An object of the present invention is to provide a solution processing apparatus capable of inhibiting the appearance of micro bubbles and reducing poor developing.
Another object of the present invention is to provide a solution processing apparatus capable of uniformly performing solution processing on the surface of a substrate.
According to a first aspect of the present invention, there is provided a solution processing apparatus comprising a substrate holding section which horizontally holds a substrate, a supply nozzle having a plurality of discharge ports which discharge a processing solution, and arranged over a length corresponding to the width of an effective area of the substrate, a moving mechanism which moves the supply nozzle relatively to the substrate in a direction orthogonal to the direction of arrangement of the discharge ports, and a guide member provided opposite to the supply nozzle and guiding the processing solution discharged from the discharge ports to the surface of the substrate, the guide member having a central portion and side portions lowered from the central portion.
According to the aforesaid structure, the processing solution discharged from the supply nozzle is supplied onto the substrate via the guide member, whereby the impact of a collision of the processing solution against the surface of the substrate is alleviated, which, for example, inhibits micro bubbles from appearing on the substrate.
According to a second aspect of the present invention, there is provided a solution processing apparatus comprising a substrate holding section which horizontally holds a substrate, a supply nozzle having a plurality of discharge ports which discharge a processing solution, and arranged over a length corresponding to a width of an effective area of the substrate, a moving mechanism configured to move the supply nozzle relatively to the substrate, and a guide member provided for the supply nozzle and guiding the processing solution discharged from the discharge ports to a surface of the substrate.
According to a third aspect of the present invention, there is provided a solution processing apparatus comprising a substrate holding section configured to horizontally hold a substrate, a supply nozzle having a plurality of discharge ports which discharge a processing solution, and arranged over a length corresponding to a width of an effective area of the substrate, a moving mechanism which moves the supply nozzle relatively to the substrate, and a guide member provided for the supply nozzle to guide the processing solution discharged from the discharge ports to a surface of the substrate, the guide member having a central portion and both end portions lowered than the central portion.
According to the second aspect and the third aspect, since the lower edge portion of the guide member which guides the processing solution discharged from the discharge ports of the supply nozzle to the surface of the substrate is formed so that both the end portions thereof are lower than the central portion, in the supply nozzle, a supply quantity to the edge portion of the substrate is set to be larger than a supply quantity to the central portion thereof. Accordingly, when the processing solution tends to concentrate at the central portion of the substrate by the spin chuck as a substrate holding section, for example, a solution film with high uniformity is formed on the substrate owing to a balance with a phenomenon in which the processing solution tries to concentrate at the central portion of the substrate. Moreover, the processing solution discharged from the supply nozzle is supplied onto the substrate via the guide member, whereby the impact of a collision of the processing solution against the surface of the substrate is alleviated. As a result, for example, micro bubbles are prevented from appearing on the substrate.
Furthermore, when the moving mechanism of a scan method for moving the supply nozzle relatively to the substrate in a direction orthogonal to the direction of arrangement of the discharge ports as in the second aspect is used, the processing solution spills at the edge portion of the substrate to the outside of the substrate. However, part of the processing solution spilling to the outside of the substrate at this time is attracted to the inside of the substrate by the surface tension of the processing solution applied on the surface of the substrate. As a result, a waviness phenomenon occurs on the surface of the substrate, and thus the processing solution concentrates at the central portion of the substrate. Hence, a solution film at the central portion of the substrate becomes thicker than at the edge portion, which causes a problem that line width becomes ununiform. In the supply nozzle, however, a supply quantity to the edge portion of the substrate is set to be larger than a supply quantity to the central portion thereof. As a result, a solution film with high uniformity is formed on the substrate.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.